Dark-field Microscopy: Principles, Use, Advantages and Limitations

Dark-field microscopy is a technique that can be used for the observation of living, unstained cells and microorganisms. In this microscopy, the specimen is brightly illuminated while the background is dark. It is one type of light microscopes, other being bright-field, phase-contrast, differential interface contrast, and fluorescence.

Principle

Principle of Dark-Field Microscopy(Image courtesy: Olivier Haeberlé)

Dark-field microscopy uses a light microscope with an extra opaque disc underneath the condenser lens, or a special condenser having a central blacked-out area, due to which the light coming from the source cannot directly enter into the objective.

The path of the light is directed in such a way that it can pass through the outer edge of the condenser at a wide-angle and strike the sample at an oblique angle. Only the light scattered by the sample reaches the objective lens for visualization. All other light that passes through the specimen will miss the objective, thus the specimen is brightly illuminated on a dark background.

Uses of Dark-Field Microscopy

Dark-field microscopes are used in the microbiology laboratory for the following purposes;

Share this:

Related

I am working as Microbiologist in National Public Health Laboratory (NPHL), government national reference laboratory under the Department of health services (DoHS), Nepal. Key areas of my work lies in Bacteriology, especially in Antimicrobial resistance.

The advent of Electron Microscopy in 1932 opens the door to visualizing small subcellular structure and viruses which were beyond the scope of Light microscopy which can’t resolve objects separated by less than 0.2μm. Facts: […]

Foldscope is a paper microscope that is built by folding the paper in origami fashion. Prof. Manu Prakash and Jim Cybulski at Stanford University invented it during 2012. Unlike conventional microscope, foldscope does not require […]

Fluorescence microscopy is a type of light microscope that works on the principle of fluorescence. A substance is said to be fluorescent when it absorbs the energy of invisible shorter wavelength radiation (such as UV […]